The care and cutting of the grasses is one of the most costly and time consuming aspects of golf course maintenance. The grasses provide the playing surface for the game as well as a beautiful and relaxing setting for recreational activity. Golf courses typically have several different varieties of grass growing in the various areas. These grasses are maintained at specific heights for tournament play and for recreational play. The equipment used to cut the grass is not only expensive but also costly to operate. Typically, the golf course superintendent will tour the golf course periodically and spot check the grass height on the greens, fairways and roughs with a ruler or by visual observation. For example, fanning is one method of visual observation. Fanning is the process of brushing of one's hand over the top of the grass to estimate grass height.
The precision of the measurements taken on the fairways and roughs is adversely affected by variations in the soil surface and by the accumulation of thatch, i.e. dried grass clipping and organic matter accumulated at the base of the grass stems. Mowing assignments are based upon relatively few measurements. Further mower height usually is set on a shop floor or other surface which exhibits less surface variation than the soil underlying the fairways, the primary roughs and the secondary roughs. Not surprisingly, much of the mowing done accomplishes little more than fanning the grass.
For example, fanning the grass with a mower may occur when a golf course superintendent, after touring the golf course generally and making occasional visual inspections of isolated spots, instructs the mower operator to cut the 6th fairway to a desired height of two inches with a maximum permissible height of four inches. Upon reaching the 6th fairway, the operator discovers that in fact the fairway grass height is close to but still under four inches. An operator who proceeds to cut the fairway at four inches because he was told to even though no grass is actually being cut is said to be just fanning the grass. The useless wear and tear on expensive mowing equipment and time in operation when just fanning by mower, multiplied by the numerous cuttings throughout the grass growing season amounts to a significant and undesirable waste of time and money.
A ruler is not a suitable tool for measuring grass height because it measures the height of the grass at only a small area, essentially at a point. In order to obtain a precise measurement of grass height using a ruler, one must average a number of measurements. Other hand measuring tools, such as the gauge proposed by John Cardinale (U.S. Pat. No. 3,973,327), also establish a soil reference by bringing the narrow edge of a gauge into contact with the soil surface. The elongated Cardinale gauge, like the ruler, measures grass height in a small area approximating a single point and a number of measurements must be averaged to obtain a precise measurement of grass height. Like the ruler, the Cardinale gauge may come to rest against a layer of thatch, a twig or other debris thereby throwing off the accuracy of the measurement.
The precision of the measurements made with such devices is also adversely affected by variations in the underlying soil surface. While such tools may measure with sufficient precision for ordinary home lawn care, they do not provide the degree of precision needed for golf course maintenance and other applications in which greater precision is required.